Disc Material Research Articles

Radial Displacements in a Rotating Disc of Uniform Thickness Made of Functionally Graded Material

The finite element method is used to calculate a rotating disc, which has a uniform thickness and is made of functionally graded materials, based on the concepts of multilayer disc and equivalent material. These concepts are also available for analytical calculus. The multilayered disc concept perceives the disc as constructed from several layers, and the equivalent material concept regards the disc material as composed of homogeneous and isotropic material but with fictitious properties equivalent in behavior to the functionally graded material. These two concepts, encompassed in this study, allow us to contemplate the variation according to the material law and Poisson's ratio, which is often neglected, to reduce the mathematical complexity. The concepts, models, and methods involved in this study were validated by employing numerical and analytical calculations. The proposed method introduced simplicity, precision, and accessibility to solve the complex problem of functionally graded structures. The calculus development, model validation, and result analysis were based on numerical calculus using the finite element method. The utilized models were grounded on the existence of an axial-symmetric plane. So, 2D or 3D simplified models can be used with several variants regarding the mesh fineness. This study results and models are useful to specialists and structure designers of this type, have a high degree of generality, and present opportunities for the application of other calculation methods.

Spontaneous resorption of a C7–T1 intervertebral disc extrusion in a Cavalier King Charles spaniel confirmed via low‐field MRI

AbstractA 4‐year‐old, male, neutered Cavalier King Charles spaniel was referred to the neurology service with a 10‐day history of cervical hyperaesthesia. A low‐field magnetic resonance imaging scan of the cervical spine identified a large C7–T1 intervertebral disc extrusion, resulting in severe spinal cord compression. The patient was treated with conservative therapy (exercise restriction and analgesia for 4 weeks). Repeat magnetic resonance imaging of the cervical spine was performed 4 months after initial presentation, and identified spontaneous resorption of the extruded C7–T1 disc material. There are very few documented cases of spontaneously resorbed cervical intervertebral disc extrusions in canine patients following successful conservative therapy. To the authors’ knowledge, this is the first report of spontaneous resorption of an intervertebral disc extrusion at an unusual C7–T1 location confirmed via follow‐up low‐field magnetic resonance imaging following conservative therapy.

Clinical and imaging findings in dogs with nerve root signature associated with cervical intervertebral disc herniation.

Intervertebral disc herniation (IVDH) is the most common spinal cord disease in dogs. Little information is available regarding the clinical presentation of nerve root signature (NRS) associated with cervical IVDH. To detail the clinical and magnetic resonance imaging (MRI) findings in dogs with NRS associated with cervical IVDH. Forty-seven client-owned dogs presenting with thoracic limb NRS and MRI confirmed IVDH. Medical records from 2010 to 2020 were retrospectively reviewed for dogs that met inclusion criteria. Imaging studies were evaluated by 2 individuals to characterize location and severity of neural tissue compression. Chondrodystrophoid dogs comprised the majority of the study cohort, with dachshund the most common breed (n = 10). Three-quarters of dogs were ≥7 years of age. Interobserver agreement was moderate or good for all of the imaging variables evaluated. The C6-C7 intervertebral disc space was significantly overrepresented (P = .01), comprising 32% (15/47) of the affected discs. However, 42% (20/47) of cases involved C2-C3 though C4-C5 disc sites. Disc material was more frequently located laterally compared to medially within the vertebral canal (P = .0005), and to be associated with compression of the nerve root at the level of the intervertebral foramen (P = .012). NRS is most commonly associated with lateralized or foraminal cervical disc herniations. It is most prevalent with C6-C7 intervertebral disc involvement, suggesting that there might be unique anatomic factors that contribute to development of NRS at this site, but can be a clinical manifestation of IVDH occurring anywhere along the cervical spine.

A 3D-Printed Piezoelectric Microdevice for Human Energy Harvesting for Wearable Biosensors.

The human body is a source of multiple types of energy, such as mechanical, thermal and biochemical, which can be scavenged through appropriate technological means. Mechanical vibrations originating from contraction and expansion of the radial artery represent a reliable source of displacement to be picked up and exploited by a harvester. The continuous monitoring of physiological biomarkers is an essential part of the timely and accurate diagnosis of a disease with subsequent medical treatment, and wearable biosensors are increasingly utilized for biomedical data acquisition of important biomarkers. However, they rely on batteries and their replacement introduces a discontinuity in measured signals, which could be critical for the patients and also causes discomfort. In the present work, the research into a novel 3D-printed wearable energy harvesting platform for scavenging energy from arterial pulsations via a piezoelectric material is described. An elastic thermoplastic polyurethane (TPU) film, which forms an air chamber between the skin and the piezoelectric disc electrode, was introduced to provide better adsorption to the skin, prevent damage to the piezoelectric disc and electrically isolate components in the platform from the human body. Computational fluid dynamics in the framework of COMSOL Multiphysics 6.1 software was employed to perform a series of coupled time-varying simulations of the interaction among a number of associated physical phenomena. The mathematical model of the harvester was investigated computationally, and quantification of the output energy and power parameters was used for comparisons. A prototype wearable platform enclosure was designed and manufactured using fused filament fabrication (FFF). The influence of the piezoelectric disc material and its diameter on the electrical output were studied and various geometrical parameters of the enclosure and the TPU film were optimized based on theoretical and empirical data. Physiological data, such as interdependency between the harvester skin fit and voltage output, were obtained.

Residual volume of extruded disc material and residual spinal cord compression measured on postoperative MRI do not predict neurological outcomes in dogs following decompressive surgery for thoracolumbar intervertebral disc extrusion.

Published studies on the validity of using quantitative MRI measures of pre- and postoperative spinal cord (SC) compression as prognostic indicators for dogs undergoing surgery for intervertebral disc extrusion (IVDE) are currently limited. The aim of this retrospective analytical study was to describe the volume of postoperative residual extradural material (VREM) and the ratio of the cross-sectional area (CSA) of maximum SC compression to the CSA of SC in a compression-free intervertebral space as MRI measures of preoperative and postoperative compression (residual spinal cord compression, RSCC), and to compare these measures between the neurological outcome in a group of dogs. Inclusion criteria were dogs that underwent surgery for thoracolumbar IVDE, were imaged pre- and immediately postoperatively by MRI, and had a neurological follow-up examination 2 to 5 weeks postoperatively. Two blinded observers independently performed measurements in pre- and postoperative MRI studies. Dogs were classified into positive outcome (PO) and negative outcome (NO) groups based on follow-up neurologic examination scores. Seventeen dogs were included (12 PO, 5 NO). Interobserver agreement for MRI measurements was good to excellent (ICCs: 0.76-0.97). The prevalence of residual extradural material in postoperative MRI studies was 100%. No significant differences in mean preoperative SC compression, mean RSCC, mean SC decompression, or VREM were found between outcome groups (P=.25; P=.28; P=.91, P=.98). In conclusion, neither postoperative VREM nor RSCC could predict successful neurological outcomes.

Physiotherapy Intervention for Cervical Radiculopathy: A Case Report

Introduction: The objective of this study is to determine the efficacy of physiotherapy on pain and quality of life in cervical radiculopathy. Cervical Radiculopathy is characterised by compression of the nerves by either arthritic bone spurs or herniated disc material. Usually, this impingement causes motor dysfunction in the upper extremities and neck, as well as sensory impairments, numbness, or discomfort extending to the arms. Pathologies affecting the nerve roots might result in cervical radiculopathy. Case Report: This case report focuses on a 31-year-old female patient who has been diagnosed with cervical radiculopathy. She had tingling and numbness in her hands, particularly in right arm of physiotherapy on pain and quality of life in cervical radiculopathy. Cervical Radiculopathy is characterised by compression of the nerves by either arthritic bone spurs or herniated disc material. Usually, this impingement causes motor dysfunction in the upper extremities and neck, as well as sensory impairments, numbness, or discomfort extending to the arms. Pathologies affecting the nerve roots might result in cervical radiculopathy. Case Report: This case report focuses on a 31-year-old female patient who has been diagnosed with cervical radiculopathy. She had tingling and numbness in her hands, particularly in right arm shows (median nerve distribution). Patient was recruited on the basis of special test: Spurling Test, Distraction Test, and Upper Limb Tension Test. After 2 week of intervention significant improvement was shown by using- Numeric pain Rating scale for pain, Neck Disability Index for Disability, and SF_12 for quality of life, patient reported less symptomatic and symptoms reduction during work and exercise. This case report demonstrates an effective, evidence based approach to physical therapy treatment for patients in cervical radiculopathy.

Relationship between the severity of neurological signs in dogs with thoracolumbar intervertebral disc disease and the magnitude of spinal cord compression by disc extrusion as assessed by computed tomography

The aim of this study was to verify the relationship between the degree of severity of neurological signs in dogs with thoracolumbar intervertebral disc disease (TL-IVDD) and the magnitude of spinal cord compression on the computed tomography (CT) transverse view of the vertebra at the site of the greatest narrowing of the spinal canal caused by extruded disc material. In a total of 78 dogs with TL-IVDD, the greatest narrowing of the spinal canal at the site of greatest spinal cord compression was observed in the T11-T12 region (48.35 ± 20.70%) and the smallest in the L2-L3 region (33.06 ± 15.40%). There was a significant difference in the percentage of spinal canal narrowing between the L2-L3 region and the T11-T12 (P = 0.034), T12-T13 (P = 0.033) and T13-L1 (P = 0.022) regions, respectively. Females showed a significantly higher percentage of spinal canal narrowing compared to males (P = 0.029); the highest percentage of spinal canal narrowing was found in neutered females compared to intact females (P = 0.013), neutered males (P = 0.029), and intact males (P = 0.001), respectively. In addition, the dogs included in the study were divided into a group of chondrodystrophic (n = 55) and a group of nonchondrodystrophic (n = 23) dogs. Dogs of chondrodystrophic breeds generally showed a highly significantly (P = 0.001) more severe degree of neurological signs compared to dogs of nonchondrodystrophic breeds. Results of this study can be useful in veterinary practice diagnostics.

Clinical features of early recurrence of type I thoracolumbar intervertebral disk herniation in Miniature Dachshunds.

Some reports have been published on clinical features in dogs with early recurrence of type I thoracolumbar intervertebral disk herniation (TL-IVDH), but there is little understanding of the changes involved. This retrospective study describes the clinical features, including radiographic image results at the time of recurrence, of dogs with type I TL-IVDH that had undergone hemilaminectomy but then suffered early recurrence. Our medical records were searched between June 2007 and December 2022. Nine dogs showed deterioration in neurological signs within 4 to 6 weeks after surgery. All nine were Miniature Dachshunds. Radiographic images at initial onset showed calcification at the affected intervertebral disk space in all 9 dogs. Disk herniations at the initial onset were located between T11-12 and L1-2. After the first surgery, neurological function improved in all dogs. Recurrence occurred at the same site as at initial onset in all dogs. No calcification was observed at the affected intervertebral disk space on images at the time of recurrence. The extruded disk materials were surgically removed, and neurological function improved after the second surgery. In conclusion, calcification at the affected disk space at the time of initial onset is indicative of residual nucleus materials not yet fully extruded, and is a risk factor for early recurrence of type I TL-IVDH.

Thermo-mechanical behavior of 2D functionally graded porous-auxetic metamaterial rotating disk with an auxetic foundation

In the present study, the thermo-mechanical behavior of two-directional functionally graded porous-auxetic metamaterial rotating disk (2D-FGPAMRD) has been analyzed. The rotating disk subjected to combination of transient thermal and steady mechanical loads and supported by an auxetic foundation. Haber-Schaim (H-S) frictionless elastic foundation model is considered to drive the structure-structure interaction. The governing equations are obtained based on the thermoelasticity theory. The response of disk to mechanical and thermal loads has been obtained by solving nonhomogeneous governing equations. To this end, the alternating direction implicit (ADI) finite difference scheme and combination of state-space and differential quadrature (DQ) methods have applied to solve the Fourier heat conduction and thermoelasticity equations, respectively. In the numerical examples, the effects of porosity and auxeticity, as well as inhomogeneity indices of the disk on its thermo-mechanical behavior have been investigated for the first time. The results reveal that, the elastic field components of rapid heating disk are significantly affected by the nature of temperature diffusion, inhomogeneity indices and the auxeticity of the disk material. Besides, the changes of thermal expansion gradient indices provide a relaxation in the normal transverse stress.

Hydrodynamic behaviour improvement of check valves through CFD analysis

In this article, the computer assisted design, flow simulation, optimization of production parameters and unique design prototype manufacturing of a check valve with 16 bar pressure, 5 m/s flow rate and 52000 m3/h flow coefficients, which have never been achieved before in the valve sector, were presented to the attention of the readers. Check valves have a critical role that do not allow reverse flow of the fluid passing through them and are generally designed to secure the pipeline. A small mistake in design may cause great damage in the system. For this reason, a new product of which the disc material exposed to 5 m/s fluid velocity, the body subjected to 16 bar pressure and the system with a flow coefficient of 52000 m3/h were designed by the Solidworks, the flow was simulated with CFD (Computational Fluid Dynamics), and the mechanical resistance was analysed by FEA (Finite Element Analysis). Fluent, CFD and mechanical modules of ANSYS were used to define the parameters of the design. The manufactures of the products designed in the computer environment have been produced by casting method with a 45% ferritic microstructure and impact resistance twice as high as the standard requirements have been implemented.

Primary osteoarthritis of the lumbar spine presenting as chronic low back pain or sciatica or both (prolapsed lumber disc syndrome): establishing its cause, pathogenesis, and treatment: A randomized case-control study

: The objectives of this study were to compare three scores, Western Ontario McMaster Universities Osteoarthritis Index (WOMAC), Oswestry Disability Index (ODI) for low back pain, and Visual Analogue Scale (VAS) Vertical Version at the beginning and end point in two, Trial (G1), and Control (G2) groups of Primary Osteoarthritis of lumbar spine patients.The inner nucleus pulposus may rupture out from the annulus as the disc continues to degrade or as the spine continues to be stressed. This is a herniated or burst disc. The nerve roots that are immediately behind the disc space may then be pressed by the disc material fragments. This may result in discomfort, frailty, numbness, or alterations in feeling.: Understanding the causes, pathophysiology, and treatments for prolapsed lumber disc syndrome, which presents as primary osteoarthritis of the lumbar spine and causes chronic low back pain, sciatica, or both.: In this study, the total number of patients were 150, in G1 - 100, and G2 - 50. G1 received the hypothesized treatment, Contracture Correction Therapy (CCT), while G2 did “No Therapy”. WOMAC determination was done by the questionnaire; ODI by modified Oswestry Low Back pain disability questionnaire and VAS by Visual Analogue Scale Vertical Version, all at 0, 6, 12, and 24 weeks. The CCT consisted of 1. Immobilization of the spine. 2. Passive and active extension of the spine. 3. Three therapeutic rituals and 4. Advice to avoid stooping.: The CCT receiving was associated with much recovery (P <0.00) while non-receiving with much less (P =0.00). In G1 WOMAC decreased from 54.29 to 0.00; ODI from 51.82 to 1.80; VAS rose from 37.56 to 100 (rise indicates betterment) P= 0.00. In G2 WOMAC lowered from 56.40 to 4.08; ODI from 65.10 to 6.0; VAS rose from 34.40 to 81.00. Relief in symptoms was similar.: The cause, pathogenesis, and treatment are deficient full extension, I.V. joint capsule contracture formation, and extension of the lumbar spine respectively.

ENSURING RELIABILITY AND RESOURCE CONSERVATION COULTERS DISCS OF GRAIN SEEDERS

A study was conducted aimed at studying the problems of the reliability of coulter discs and proposing ways, methods of restoring and optimizing the design of coulters of grain seed drills to maximize their reliability and durability. Grain planters in agriculture play a key role in the process of growing crops. However, one of the most important components of these units are coulter discs, which are often exposed to aggressive conditions and heavy physical loads. Ensuring the reliability of coulter discs of grain seeders is a key aspect in agricultural production, since the efficiency of the technological process of sowing directly affects the yield and quality of agricultural crops. A thorough analysis of the geometry and materials of the disks was carried out to identify weak points and potential sources of activation, as well as to determine the main factors that lead to their wear and destruction. The values and distribution of the residual stresses in the material of the new disk and the restored one by welding three segments made of steel with surmite surfacing and vibration hardening were determined. The values of the degree of strengthening of the material of the cutting edge of restored coulter discs were found. Optimal modes of vibration strengthening are established: frequencies and amplitudes of oscillations of the processing tool, time. The research makes it possible to develop an optimized design of opener discs, which will ensure their high reliability and service life during various operating conditions. The results of the research will be used to improve the technical characteristics and production technologies of coulter discs, which will help to increase productivity, reduce the costs of repairing seed drills and ensure efficient sowing.

THE FORMATION AND THE EVOLUTION OF LARGE-SCALE VORTEX STRUCTURES IN STELLAR ACCRETION DISKS

Explaining the causes of angular momentum transfer in accretion stellar disks is an important astrophysical problem, since it is the process that determines the rate of accretion of matter onto the central gravitating body. Previously, within the framework of a two-dimensional approach, it was shown that the introduction of small perturbations into the flow of disk matter leads to the appearance of shear instability. This process is accompanied by the development of large-scale vortex structures. Their movement and evolution lead to a redistribution of angular momentum in the accretion disk. The action of the described mechanism was previously studied numerically only within a two-dimensional approximation, so the goal of the current work is to carry out full-scale three-dimensional modeling. The processes under study are described within the framework of the system of equations of ideal gas dynamics. The article briefly describes the method for their numerical integration, which is based on a conservative finite-difference scheme and the solution of the Riemann problem. The initial data is a stationary toroidal gas state surrounded by a matter with low density and pressure. At the next step, small perturbations of one of the gas-dynamic variables are introduced. The modeling and analysis of the results of numerical calculations show the emergence of vortex structures in the shear flow of a three-dimensional accretion disk. Their movement is accompanied by a redistribution of matter and angular momentum in the volume of the disk, leading to accretion of matter onto the central body.

Investigation on influence of polishing disc materials in UV-catalytic polishing of single crystal diamond

The effects of three materials (Fe, SiO2, Al2O3) on the tribological behavior and material removal process of single crystal diamond (SCD) in a UV-catalyzed environment were investigated through ball-on-disc friction and wear experiments, as well as CMP experiments. The results indicate that the material removal rate (MRR) of SCD increases with the hardness of the polishing disc material. However, the surface roughness Ra is influenced by the synergistic effect of both chemical and mechanical actions. Strong chemical action leads to C-O corrosion on the surface, while strong mechanical action causes sp2 damage to surface C atoms. When using Al2O3 discs, the MRR is the highest, reaching 713.5 nm/h, while SiO2 discs result in a smooth surface with a surface roughness Ra of 0.26 nm. Therefore, the SCD can be rough polished with Al2O3 discs first and then fine polished with SiO2 discs to achieve a high material removal rate and superior surface quality simultaneously.

Effects of thermal cycling treatment on load bearing and friction behavior of SiCp/A356 composites

During bench tests and actual service, the Al-MMC (metal matrix composite) brake discs used in urban rail transit vehicles experienced problems such as poor wear resistance, compromising the brake discs' stability and safety. While braking, the brake disc material will bear the thermal cycling loads, leading to a certain degree of degradation in the material's performance. In this study, the degradation of the material's performance by the thermal cycling treatment was investigated. The results showed that all material performance degraded to some extent after thermal cycling treatment, with a strong correlation with cycling temperature. The degradation of material performance was caused by a combination of matrix mechanical damage and interface damage. At the same time, the tribological performance of the material also decreased to some extent. The main effect of thermal cycling treatment on tribological performance was its effect on material performance. The increase of hard particles in the abrasive debris resulting from the mechanical damage of the material and the aggravation of the dynamic changes in the TBL (third body layer) were the basic reasons for the surface scratches. The results further help to explore the application of Al-MMCs in high-temperature and long-term service.

Study on the mechanism of mechanical properties deterioration of brake disc materials of high-speed train

The mechanical properties of high-speed train brake disc will deteriorate after service, it is necessary to study the degradation mechanism in order to better understand the service process of the material. In this study, the microstructure evolution of the material in the hot spot area of the brake disc was observed by microstructure analysis, and a mixed structure of coarse and fine grains was formed. Through DIC tensile test and in-situ tensile test, the mechanism of mechanical property degradation of brake disc was obtained. The fine grain zone in the hot spot area forms a constraint effect on the coarse grain zone, resulting in uncoordinated deformation. It further causes strain localization and micro-cracks, resulting in a decrease in the bearing capacity and strength of the material. According to EBSD analysis, it is found that the distribution difference of grain boundary orientation further increases the degree of uncoordinated deformation between coarse and fine grains, resulting in stress concentration at the junction and inducing the formation of microcracks. The research results provide guidance for crack damage identification of brake disc. It is suggested that attention should be paid to the change of microstructure during the condition-based maintenance of brake disc, which is of great significance to ensure the safe operation of high-speed trains.

High-angular-resolution Imaging of the V892 Tau Binary System: A New Circumprimary Disk Detection and Updated Orbital Constraints

We present a direct imaging study of V892 Tau, a young Herbig Ae/Be star with a close-in stellar companion and circumbinary disk. Our observations consist of images acquired via Keck II/NIRC2 with nonredundant masking and the pyramid wavefront sensor at band (2.12 μm) and band (3.78 μm). Sensitivity to low-mass accreting companions and cool disk material is high at band, while complimentary observations at band probe hotter material with higher angular resolution. These multiwavelength, multiepoch data allow us to differentiate the secondary stellar emission from disk emission and deeply probe the structure of the circumbinary disk at small angular separations. We constrain architectural properties of the system by fitting geometric disk and companion models to the - and -band data. From these models, we constrain the astrometric and photometric properties of the stellar binary and update the orbit, placing the tightest estimates to date on the V892 Tau orbital parameters. We also constrain the geometric structure of the circumbinary disk, and resolve a circumprimary disk for the first time.

Histopathological spectrum of lumbar disc changes in obesity: analysis of intervertebral discs in lumbar hernia patients in Zenica-Doboj Canton, Bosnia and Herzegovina

<p><strong>Aim</strong> <br />To investigate the correlation of body mass index (BMI) with severity of intervertebral disc degeneration.<br /><strong>Methods <br /></strong>The study enrolled patients who had undergone surgical intervention for a herniated disc at the Department of Neurosurgery of the Cantonal Hospital Zenica. Patients underwent thorough preoperative evaluation, including medical history, neurological and physical assessments, and radiological analysis. The surgical intervention consisted of a posterior lumbar discectomy, and the excised disc material was preserved and subjected to histopathological analysis based on Histopathologic Degeneration Score (HDS). Patients were divided in two groups according to Body Mass Index (BMI): study group with BMI≥25 and control group with BMI<25.<br /><strong>Results</strong> <br />Among 69 patients with herniated IVD, 26 (37.7%) were with BMI≥25 (study group), and 43 (62.3%) were with BMI<25<br />(controls). The study group displayed substantial increase in height, 1.80±0.06 m compared to controls, 1.74±0.06 m (p=0.001). Weight and BMI were significantly higher in the study group of patients (weight: 91.60±10.22 vs. 67.37±9.20 kg, BMI: 28±2 vs. 22±2; p<0.001). Differences were confirmed in HDS values in the study group comparing to the control group (p<0.001). The study group exhibited significant differences in chondrocyte proliferation, tears and clefts, granular changes, and mucous degeneration (p<0.05), and positive correlations were found between BMI and<br />these alterations found in the herniated discs (p<0.05). Therefore, HDS showed positive correlations with BMI (R=0.599; p<0.001) and weight (R=0.696; p<0.001).<br /><strong>Conclusion</strong> <br />The study's findings confirmed that BMI has a significant impact on intervertebral disc degeneration, emphasizing the<br />importance of weight management in preventing disc degeneration.</p>

High-energy Neutrino Emission Associated with GWs from Binary Black Hole Mergers in AGN Accretion Disks

The search for multimessenger signals of binary black hole (BBH) mergers is crucial to understanding the merger process of BBH and the relative astrophysical environment. Considering BBH mergers occurring in the active galactic nuclei (AGN) accretion disks, we focus on the accompanying high-energy neutrino production from the interaction between the jet launched by the postmerger remnant BH and disk materials. Particles can be accelerated by the shocks generated from the jet–disk interaction and subsequently interact with the disk gas and radiations to produce high-energy neutrinos through hadronic processes. We demonstrate that the identification of the high-energy neutrino signal from BBH merger in AGN disks is feasible. In addition, the joint BBH gravitational wave (GW) and neutrino detection rate is derived, which can be used to constrain the BBH merger rate and the accretion rate of the remnant BH based on the future associated detections of GWs and neutrinos. To date, an upper limit of BBH merger rate density in AGN disks of R 0 ≲ 3 Gpc−3 yr−1 is derived for the fiducial parameter values based on the current null association of GWs and neutrinos.

A re-assessment of Ti-685 as a dwell sensitive titanium alloy and a definition for engineering relevant dwell behaviour

It is believed that the near-α titanium alloy Ti-685 was the first to demonstrate dwell sensitive fatigue behaviour whilst under engineering service as a gas turbine fan disc material. New fatigue data, micro-textural characterisation and fractography from a recent study which utilised remnant Ti-685 specimens originally manufactured for previous laboratory campaigns based at Swansea dating back to the late 1980s are now reported. In isolation, the present results failed to demonstrate a significant dwell effect in either aligned or basketweave microstructural variants. On this occasion, the limited sensitivity to dwell loading was explained by the combination of heat treatment artifacts and selection of a relatively small test specimen geometry. However, the present data were also reviewed in the context of the wider fatigue database generated by multiple studies over the past fifty years. In combination, stress-life (SN) curves defined the magnitude in applied peak stress necessary to demonstrate a dwell effect in this alloy. Ultimately, this facilitated a fundamental definition of dwell sensitivity that is relevant to the engineering community.